Robust Sliding Mode Control for Air-to-Air Missile

TL;DR

This paper develops a robust second order sliding mode controller for air-to-air missiles that effectively manages uncertainties in flight dynamics and sensor noise, ensuring precise tracking with minimal overshoot and rapid settling time.

Contribution

It introduces a novel exponential reaching law for sliding mode control that reduces chattering and maintains high performance despite model uncertainties and measurement noise.

Findings

Achieves 0.2s settling time and 3% overshoot in ideal conditions.

Maintains 5% steady state error with sensor noise at 200Hz.

Demonstrates superior chattering mitigation over traditional methods.

Abstract

Within the missile guidance and control system the autopilot must overcome an array of variables and uncertainties to maintain tracking trajectory. A large uncertainty explored in this paper is the difference between the assumed flight dynamics, the controller design relies on, and the true flight dynamics the missile experiences. To capture these differences experimental wind tunnel data was used to represent real life aerodynamics whereas a low fidelity wing and tube structure was used for the controller dynamics. Other variables affecting controller performance are also quantified and explored in this paper, such as the changing mass, center of gravity, dynamic pressure, actuator bandwidth and sensor noise. A second order sliding mode controller utilizing an exponential reaching law was developed to overcome the cumulative uncertainties. The designed controller is capable of a 0.2s settling time and a 3% overshoot in ideal conditions. The controller relies on measurements of both dynamic pressure and angle of attack, when a 10% and 2% respective noise is introduced at 200Hz, the controller maintains a 5% steady state error and a time constant of 0.29s. The exponential reaching law provides superior chattering mitigation over traditional techniques like the tanh function, with no loss in controller performance.